Factually inaccurate. The bread for the hot dog is cut vertically while the sub's bread is cut horizontally. You also cut the meat into smaller pieces for subs, while you leave the hot dog itself intact. If you cut the hot dog into pieces and put it into a horizontally sliced bun it would be a sandwich, but I feel that the way the hot dog is served is too differently than a conventional sandwich to be called one.

By this logic a sandwich can be a sandwich or not depending on its contents?
If i put a full hotdog in between two slices of white bread and eat it as such, is that a sandwich or a hot dog?
If i cut a hot dog down the middle all the way and put the two halves in a hot dog bun, is it still a hotdog despite the dog itself not being intact?